U.S. patent application number 13/400799 was filed with the patent office on 2013-08-22 for elastic supporting structure and optical image stabilizer having the elastic supporting structure.
This patent application is currently assigned to TDK TAIWAN CORP.. The applicant listed for this patent is Shih-Ting Huang, Jyun-Jie Lin, Fu-Yuan Wu. Invention is credited to Shih-Ting Huang, Jyun-Jie Lin, Fu-Yuan Wu.
Application Number | 20130215511 13/400799 |
Document ID | / |
Family ID | 48982097 |
Filed Date | 2013-08-22 |
United States Patent
Application |
20130215511 |
Kind Code |
A1 |
Wu; Fu-Yuan ; et
al. |
August 22, 2013 |
Elastic supporting structure and optical image stabilizer having
the elastic supporting structure
Abstract
An elastic supporting structure for an optical image stabilizer
is provided. The optical image stabilizer includes a movable
portion, a compensation module, and a plurality of suspension
wires. The movable portion is provided therein with a lens. The
compensation module corresponds to the movable portion, and both
are located on the same image-capturing optical axis. Each
suspension wire has two ends respectively connected to the movable
portion and the compensation module. The movable portion is
provided with an upper spring plate. One end of each suspension
wire is connected to a length-increased outer line element and at
least one additional auxiliary line element of the upper spring
plate, and the other end of each suspension wire is connected to
the compensation module, such that the movable portion corresponds
to the compensation module and is spaced therefrom by a
predetermined distance. Also, anti-shake function performs well
with suspension wires.
Inventors: |
Wu; Fu-Yuan; (Yangmei,
TW) ; Huang; Shih-Ting; (Yangmei, TW) ; Lin;
Jyun-Jie; (Yangmei, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Wu; Fu-Yuan
Huang; Shih-Ting
Lin; Jyun-Jie |
Yangmei
Yangmei
Yangmei |
|
TW
TW
TW |
|
|
Assignee: |
TDK TAIWAN CORP.
Taipei City
TW
|
Family ID: |
48982097 |
Appl. No.: |
13/400799 |
Filed: |
February 21, 2012 |
Current U.S.
Class: |
359/554 |
Current CPC
Class: |
H04N 5/23287 20130101;
G02B 27/646 20130101 |
Class at
Publication: |
359/554 |
International
Class: |
G02B 27/64 20060101
G02B027/64 |
Claims
1. An elastic supporting structure for an optical image stabilizer,
the optical image stabilizer comprising a movable portion, a
compensation module, and a plurality of first elastic elements, the
optical image stabilizer defining an X-axis direction, a Y-axis
direction, and a Z-axis direction which are mutually perpendicular,
the movable portion being provided therein with a lens, the lens
defining an image-capturing optical axis parallel to the Z-axis
direction, each said first elastic element having two ends
respectively connected to the movable portion and the compensation
module such that the movable portion is supported and secured above
the compensation module in the Z-axis direction, the movable
portion being provided with at least a second elastic element
comprising: an outer frame connected to the movable portion, an
inner frame connected to the lens, at least an inner line element
extending and connected between the outer frame and the inner
frame, and a plurality of coupling ends located on the outer frame,
each said first elastic element having a said end connected to a
corresponding said coupling end, the elastic supporting structure
being characterized in that: in each said second elastic element,
each said coupling end is connected to the outer frame by an outer
line element and at least an additional auxiliary line element,
wherein the outer line element has an end connected to the each
said coupling end and an opposite end connected to the outer frame,
and each said additional auxiliary line element has an end
connected to the each said coupling end and an opposite end
connected to the outer frame.
2. The elastic supporting structure of claim 1, wherein each said
additional auxiliary line element corresponding to a said coupling
end has a greater length than the outer line element corresponding
to the coupling end, and wherein the at least a second elastic
element and the first elastic elements are either independent and
separate components or a single, integrally formed component.
3. The elastic supporting structure of claim 1, wherein each said
first elastic element is a suspension wire having a structure
selected from the group consisting of: a single-line structure
extending along the Z-axis direction, a suspension wire structure
having a continuous S-shaped flexible portion, and a suspension
wire structure having a spiral spring-shaped flexible portion.
4. The elastic supporting structure of claim 1, wherein each said
second elastic element is a spring plate, and the outer frame of
each said spring plate has a rectangular structure and at least two
adjacent sides, each said coupling end being located adjacent to a
corner of a said outer frame having the rectangular structure, the
outer line element and the at least an additional auxiliary line
element corresponding to each said coupling end of a said outer
frame being connected to two adjacent said sides of the outer frame
respectively.
5. The elastic supporting structure of claim 4, wherein each said
first elastic element is a suspension wire having a length ranging
from 2 mm to 3 mm, having a diameter ranging from 0.04 mm to 0.05
mm, and made of a material having a Young's modulus of 120000 MPa,
and wherein each said spring plate has a thickness ranging from 0.3
mm to 0.5 mm and is made of a material having a Young's modulus of
127000 MPa.
6. The elastic supporting structure of claim 4, wherein each said
spring plate is an upper spring plate, and the movable portion is
an automatic focusing module comprising: a base; a lens holder
provided in the base; a coil wound around the lens holder; a
plurality of magnets located on an inner periphery of the base and
corresponding to the coil, the magnets and the coil jointly forming
an electromagnetic driving module for driving the lens holder to
move along the image-capturing optical axis; a lens located on the
image-capturing optical axis and provided in the lens holder; an
upper cover plate covering the lens holder; an insulating plate
located between the upper cover plate and the at least an upper
spring plate; a lower spring plate located in the base, the lens
holder being elastically clamped by the lower spring plate and the
at least an upper spring plate; a magnet fixing element provided at
a bottom of the base and corresponding to the compensation module;
two X-axis magnets oppositely provided on the magnet fixing
element; and two Y-axis magnets oppositely provided on the magnet
fixing element and located on lateral sides of one and the other of
the two X-axis magnets.
7. The elastic supporting structure of claim 6, wherein the
compensation module is an optical anti-shake module and comprises:
a substrate having an electric circuit and corresponding to the
base; a correction circuit board physically and electrically
connected to the substrate; two X-axis magnet driving coils
oppositely provided on the correction circuit board and
corresponding to the two X-axis magnets; two Y-axis magnet driving
coils oppositely provided on the correction circuit board, located
on lateral sides of one and the other of the two X-axis magnet
driving coils, and corresponding to the two Y-axis magnets; an
X-axis displacement sensor provided on the substrate for detecting
a shift amount of one of the two X-axis magnets; and an Y-axis
displacement sensor provided on the substrate for detecting a shift
amount of one of the two Y-axis magnets.
8. The elastic supporting structure of claim 7, wherein each of the
X-axis displacement sensor and the Y-axis displacement sensor is a
displacement sensing element composed of one of: a Hall sensor, a
magnetoresistance sensor (MR sensor), a fluxgate, an optical
position sensor, and an optical encoder.
9. The elastic supporting structure of claim 6, wherein the
suspension wires, the at least an upper spring plate, and the lower
spring plate are electrically conductive and serve as conductive
wires for delivering a driving current of the automatic focusing
module.
10. The elastic supporting structure of claim 1, further comprising
a sensing module located below the compensation module, the sensing
module comprising a circuit board and an image sensing element,
wherein the image sensing element is provided on the circuit board
and located on the same image-capturing optical axis as the movable
portion.
11. An optical image stabilizer having an elastic supporting
structure, the optical image stabilizer defining an X-axis
direction, a Y-axis direction, and a Z-axis direction which are
mutually perpendicular, the optical image stabilizer comprising: a
movable portion provided therein with a lens, the lens defining an
image-capturing optical axis parallel to the Z-axis direction; a
compensation module configured as an optical anti-shake module for
compensating for shake-induced displacements of the lens at least
in the Y-axis direction and the Z-axis direction; and a plurality
of first elastic elements, each said first elastic element having
two ends respectively connected to the movable portion and the
compensation module such that the movable portion is supported and
secured above the compensation module in the Z-axis direction;
wherein the movable portion is provided with at least a second
elastic element comprising: an outer frame connected to the movable
portion, an inner frame connected to the lens, at least an inner
line element extending and connected between the outer frame and
the inner frame, and a plurality of coupling ends located on the
outer frame, each said first elastic element having a said end
connected to a corresponding said coupling end; and wherein in each
said second elastic element, each said coupling end is connected to
the outer frame by an outer line element and at least an additional
auxiliary line element, wherein the outer line element has an end
connected to the each said coupling end and an opposite end
connected to the outer frame, and each said additional auxiliary
line element has an end connected to the each said coupling end and
an opposite end connected to the outer frame.
12. The optical image stabilizer of claim 11, wherein each said
additional auxiliary line element corresponding to a said coupling
end has a greater length than the outer line element corresponding
to the coupling end, and wherein the at least a second elastic
element and the first elastic elements are either independent and
separate components or a single, integrally formed component.
13. The optical image stabilizer of claim 11, wherein each said
first elastic element is a suspension wire having a structure
selected from the group consisting of: a single-line structure
extending along the Z-axis direction, a suspension wire structure
having a continuous S-shaped flexible portion, and a suspension
wire structure having a spiral spring-shaped flexible portion.
14. The optical image stabilizer of claim 11, wherein each said
second elastic element is a spring plate, and the outer frame of
each said spring plate has a rectangular structure and at least two
adjacent sides, each said coupling end being located adjacent to a
corner of a said outer frame having the rectangular structure, the
outer line element and the at least an additional auxiliary line
element corresponding to each said coupling end of a said outer
frame being connected to two adjacent said sides of the outer frame
respectively.
15. The optical image stabilizer of claim 14, wherein each said
first elastic element is a suspension wire having a length ranging
from 2 mm to 3 mm, having a diameter ranging from 0.04 mm to 0.05
mm, and made of a material having a Young's modulus of 120000 MPa,
and wherein each said spring plate has a thickness ranging from 0.3
mm to 0.5 mm and is made of a material having a Young's modulus of
127000 MPa.
16. The optical image stabilizer of claim 14, wherein each said
spring plate is an upper spring plate, and the movable portion is
an automatic focusing module comprising: a base; a lens holder
provided in the base; a coil wound around the lens holder; a
plurality of magnets located on an inner periphery of the base and
corresponding to the coil, the magnets and the coil jointly forming
an electromagnetic driving module for driving the lens holder to
move along the image-capturing optical axis; a lens located on the
image-capturing optical axis and provided in the lens holder; an
upper cover plate covering the lens holder; an insulating plate
located between the upper cover plate and the at least an upper
spring plate; a lower spring plate located in the base, the lens
holder being elastically clamped by the lower spring plate and the
at least an upper spring plate; a magnet fixing element provided at
a bottom of the base and corresponding to the compensation module;
two X-axis magnets oppositely provided on the magnet fixing
element; and two Y-axis magnets oppositely provided on the magnet
fixing element and located on lateral sides of one and the other of
the two X-axis magnets.
17. The optical image stabilizer of claim 16, wherein the
compensation module is an optical anti-shake module and comprises:
a substrate having an electric circuit and corresponding to the
base; a correction circuit board physically and electrically
connected to the substrate; two X-axis magnet driving coils
oppositely provided on the correction circuit board and
corresponding to the two X-axis magnets; two Y-axis magnet driving
coils oppositely provided on the correction circuit board, located
on lateral sides of one and the other of the two X-axis magnet
driving coils, and corresponding to the two Y-axis magnets; an
X-axis displacement sensor provided on the substrate for detecting
a shift amount of one of the two X-axis magnets; and a Y-axis
displacement sensor provided on the substrate for detecting a shift
amount of one of the two Y-axis magnets.
18. The optical image stabilizer of claim 17, wherein each of the
X-axis displacement sensor and the Y-axis displacement sensor is a
displacement sensing element composed of one of: a Hall sensor, a
magnetoresistance sensor (MR sensor), a fluxgate, an optical
position sensor, and an optical encoder.
19. The optical image stabilizer of claim 16, wherein the
suspension wires, the at least an upper spring plate, and the lower
spring plate are electrically conductive and serve as conductive
wires for delivering a driving current of the automatic focusing
module.
20. The optical image stabilizer of claim 11, further comprising a
sensing module located below the compensation module, the sensing
module comprising a circuit board and an image sensing element,
wherein the image sensing element is provided on the circuit board
and located on the same image-capturing optical axis as the movable
portion.
Description
BACKGROUND OF INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an elastic supporting
structure for an optical image stabilizer and, more particularly,
to an elastic supporting structure for preventing a lens module
from permanent deformation should the lens module be dropped,
thereby providing the lens module with enhanced shock
resistance.
[0003] 2. Description of the Prior Art
[0004] Digital cameras have been continuously downsized due to the
advancement of technology, and thanks to the miniaturization of
lens modules, many small electronic devices nowadays, such as
mobile phones, are equipped with digital camera functions as a
basic requirement. In order to provide automatic focusing or
zooming, the microlenses in those electronic devices are typically
driven to move by a voice coil motor (VCM), which carries a lens
and can move the lens back and forth along an image-capturing
optical axis by means of a coil, a magnet and an elastic plate.
Moreover, consumers have had higher and higher requirements for
image quality and camera functions, and it is such advanced
criteria as a 10-megapixel resolution and anti-shake systems that
distinguish high-end cameras from low-end ones.
[0005] In an optical system composed of a lens module and an image
compensation module, e.g., the optical system of a still camera or
a video camera, the optical path tends to be shifted because of
external factors or as a result of the shaking of the hand holding
the camera. Should the optical path be shifted, imaging of the
image compensation module will become unstable such that the images
captured are blurred. The most common solution is to provide a
compensation mechanism for the image blurring phenomenon caused by
shaking, wherein the compensation mechanism, either digital or
optical, serves to clarify the images captured.
[0006] The so-called digital compensation mechanism refers to
analyzing and processing the images captured by the image
compensation module so as to obtain clearer digital images. This
approach is also known as the digital anti-shake mechanism. The
optical compensation mechanism, on the other hand, refers to
providing a vibration compensation device either on an optical lens
set or on the image compensation module, and this approach is also
known as the optical anti-shake mechanism. The existing optical
anti-shake mechanisms typically involve complicated or bulky
mechanisms or components and are therefore disadvantaged by
technical complexity, difficulty of assembly, high costs, or
undesirably large volumes that cannot be further downsized. In
short, the known optical anti-shake mechanisms leave room for
improvement.
[0007] FIG. 1 is a schematic view of the optical compensation
mechanism disclosed in Japanese Patent Application Laid-Open No.
2002-207148. As shown in the drawing, the circuit substrate 301a of
the image sensor 300a is supported by the flexible elements 400a to
403a, which are made of metal wires and can move perpendicular to
the optical axis 201a. The X-axis and Y-axis displacements of the
lens element 203a (which includes the lens 200a and the lens holder
202a) relative to the circuit substrate 301a are detected by the
two relative displacement sensors 500a, 501a and the displacement
detector 503a and sent to the anti-shake controller 504a so that,
under the control of the anti-shake controller 504a and according
to the detected displacements, the driving element 502a drives the
circuit substrate 301a into corresponding movements perpendicular
to the optical axis 201a, thereby preventing the image sensor 300a
from generating blurred images which may otherwise result from the
shaking of the image sensor 300a.
[0008] However, the mechanism proposed by the afore-cited Japanese
Patent Application Laid-Open No. 2002-207148 for preventing
shake-induced blurred images is only conceptual. The invention
disclosed in the present application is based on a similar concept
but is further incorporated with an automatic focusing module,
wherein not only is resistance provided against shake-induced
lateral shifting along the X axis and the Y axis, but also the lens
element, when dropped, is protected from permanent (e.g., plastic)
deformation in the Z-axis direction (i.e., along the
image-capturing optical axis). In other words, enhanced resistance
is provided against shakes resulting from the drop impact.
SUMMARY OF THE INVENTION
[0009] The primary objective of the present invention is to provide
an elastic supporting structure for an optical image stabilizer,
wherein an additional auxiliary line element serves to reinforce an
outer line element on an upper spring plate so as to prevent an
optical lens from plastic deformation along an image-capturing
optical axis when dropped.
[0010] In order to achieve the aforementioned objective, the
present invention provides an elastic supporting structure for an
optical image stabilizer. The optical image stabilizer comprises a
movable portion, a compensation module, and a plurality of first
elastic elements. The optical image stabilizer is defined with an
X-axis direction, a Y-axis direction, and a Z-axis direction which
are mutually perpendicular. The movable portion is provided therein
with a lens. The lens defines an image-capturing optical axis
parallel to the Z-axis direction. Each first elastic element has
two ends respectively connected to the movable portion and the
compensation module such that the movable portion is supported and
secured above the compensation module in the Z-axis direction. The
movable portion is provided with at least a second elastic element
which comprises: an outer frame connected to the movable portion,
an inner frame connected to the lens, at least an inner line
element extending and connected between the outer frame and the
inner frame, and a plurality of coupling ends located on the outer
frame. Each first elastic element has its end connected to a
corresponding coupling end. Wherein, in each second elastic
element, each coupling end is connected to the outer frame by an
extended outer line element and at least an additional auxiliary
line element. Wherein the outer line element has an end connected
to each coupling end and an opposite end connected to the outer
frame, and each additional auxiliary line element has an end
connected to each coupling end and an opposite end connected to the
outer frame.
[0011] In a preferred embodiment, each additional auxiliary line
element corresponding to the coupling end has a greater length than
the outer line element corresponding to the coupling end, and
wherein the second elastic element and the first elastic elements
are either independent and separate components or a single,
integrally formed component.
[0012] In a preferred embodiment, each first elastic element is a
suspension wire having a structure selected from the group
consisting of: a single-line structure extending along the Z-axis
direction, a suspension wire structure having a continuous S-shaped
flexible portion, and a suspension wire structure having a spiral
spring-shaped flexible portion.
[0013] In a preferred embodiment, each second elastic element is a
spring plate, and the outer frame of each spring plate has a
rectangular structure and at least two adjacent sides, each
coupling end being located adjacent to a corner of a said outer
frame having the rectangular structure, the outer line element and
the at least an additional auxiliary line element corresponding to
each coupling end of the outer frame being connected to two
adjacent sides of the outer frame respectively.
[0014] In a preferred embodiment, each first elastic element is a
suspension wire having a length ranging from 2 mm to 3 mm, having a
diameter ranging from 0.04 mm to 0.05 mm, and made of a material
having a Young's modulus of 120000 MPa, and wherein each spring
plate has a thickness ranging from 0.3 mm to 0.5 mm and is made of
a material having a Young's modulus of 127000 MPa.
[0015] In a preferred embodiment, each spring plate is an upper
spring plate, and the movable portion is an automatic focusing
module comprising: a base, a lens holder provided in the base, a
coil wound around the lens holder, a plurality of magnets, a lens
located on the image-capturing optical axis and provided in the
lens holder, an upper cover plate covering the lens holder, an
insulating plate located between the at least an upper spring plate
and the base, a lower spring plate located in the base, a magnet
fixing element provided at a bottom of the base and corresponding
to the compensation module, two X-axis magnets oppositely provided
on the magnet fixing element, and two Y-axis magnets oppositely
provided on the magnet fixing element and located on lateral sides
of one and the other of the two X-axis magnets. Wherein, the
plurality of magnets are located on an inner periphery of the base
and corresponding to the coil, the magnets and the coil jointly
forming an electromagnetic driving module for driving the lens
holder to move along the image-capturing optical axis. The lens
holder is elastically clamped by the lower spring plate and the at
least an upper spring plate.
[0016] In a preferred embodiment, the compensation module is an
optical anti-shake module and comprises: a substrate having an
electric circuit and corresponding to the base, a correction
circuit board physically and electrically connected to the
substrate, two X-axis magnet driving coils oppositely provided on
the correction circuit board and corresponding to the two X-axis
magnets, two Y-axis magnet driving coils oppositely provided on the
correction circuit board, located on lateral sides of one and the
other of the two X-axis magnet driving coils and corresponding to
the two Y-axis magnets; an X-axis displacement sensor provided on
the substrate for detecting a shift amount of one of the two X-axis
magnets, and a Y-axis displacement sensor provided on the substrate
for detecting a shift amount of one of the two Y-axis magnets.
[0017] In a preferred embodiment, each of the X-axis displacement
sensor and the Y-axis displacement sensor is a displacement sensing
element composed of one of: a Hall sensor, a magnetoresistance
sensor (MR sensor), a fluxgate, an optical position sensor, and an
optical encoder.
[0018] In a preferred embodiment, the suspension wires, the at
least an upper spring plate, and the lower spring plate are
electrically conductive and serve as conductive wires for
delivering a driving current of the automatic focusing module.
[0019] In a preferred embodiment, the elastic supporting structure
further comprises a sensing module located below the compensation
module, the sensing module comprising a circuit board and an image
sensing element, wherein the image sensing element is provided on
the circuit board and located on the same image-capturing optical
axis as the movable portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The structure as well as a preferred mode of use, further
objectives, and advantages of the present invention will be best
understood by referring to the following detailed description of
some illustrative embodiments in conjunction with the accompanying
drawings, in which:
[0021] FIG. 1 is a schematic view of the mechanism disclosed in
Japanese Patent Application Laid-Open No. 2002-207148;
[0022] FIG. 2 is an exploded perspective view of the optical image
stabilizer according to the present invention;
[0023] FIG. 3 is an partially assembled perspective view of the
optical image stabilizer according to the present invention;
[0024] FIG. 4 schematically shows a spring plate in the optical
image stabilizer according to the present invention;
[0025] FIG. 5 is a partial view of a spring plate in the optical
image stabilizer according to the present invention;
[0026] FIG. 6 schematically shows a spring plate in a conventional
optical image stabilizer; and
[0027] FIGS. 7A and 7B respectively show the second and the third
embodiments of a suspension wire in the optical image stabilizer
according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] Please refer to FIGS. 2 and 3 respectively for an exploded
perspective view and a partially assembled perspective view of an
optical image stabilizer 1 according to the present invention.
[0029] The present invention provides an elastic supporting
structure for the optical image stabilizer 1, wherein the optical
image stabilizer 1 defines three axial directions that are
perpendicular to one another, namely an X-axis direction, a Y-axis
direction, and a Z-axis direction. The optical image stabilizer 1
includes a movable portion 10, a compensation module 20, a sensing
module 30, and a plurality of first elastic elements 5. In this
embodiment, the first elastic elements 5 are a plurality of
suspension wires (hence the first elastic elements also referred to
hereinafter as the suspension wires 5). The movable portion 10 is
an automatic focusing module (hence the movable portion also
referred to hereinafter as the automatic focusing module 10) or a
zooming module. The movable portion 10 is provided therein with a
lens 105, wherein the lens 105 defines an image-capturing optical
axis 7. In another embodiment (not shown), the movable portion 10
is a lens module without an automatic focusing or zooming function.
The movable portion 10 has surfaces generally parallel to the plane
defined by the X and Y axes. The compensation module 20 corresponds
to the movable portion 10 and is located on the image-capturing
optical axis 7, which is generally parallel to the Z axis. The
plural suspension wires 5 (i.e., the first elastic elements) extend
generally in parallel to the Z axis. By means of a connecting end
51 and a fixed end 52 of each suspension wire 5, the automatic
focusing module 10 is supported and secured relative to the
compensation module 20 in the Z-axis direction such that the
automatic focusing module 10, the compensation module 20, and the
sensing module 30 are located generally on the same image-capturing
optical axis 7. In addition, the optical image stabilizer 1 is
enclosed by a housing 40. The housing 40 has a through hole 401
through which the sensing module 30, which corresponds to the
automatic focusing module 10, can capture light from the
outside.
[0030] In this embodiment, the automatic focusing module 10
includes a base 101, a lens holder 102, a coil 103, a plurality of
magnets 104, the aforesaid lens 105, an upper cover plate 106, an
insulating plate 107, a second elastic element 108, a lower spring
plate 109, a magnet fixing element 110, two X-axis magnets 111, and
two Y-axis magnets 112. The compensation module 20 is an optical
anti-shake module for compensating for shake-induced displacements
of the lens 105 at least in the Y-axis direction and the Z-axis
direction. The compensation module 20 includes a substrate 201, a
correction circuit board 202, two X-axis magnet driving coils 203,
two Y-axis magnet driving coils 204, an X-axis displacement sensor
205, and a Y-axis displacement sensor 206. In the present
invention, the second elastic element 108 also has a spring-plate
structure and is located in an upper portion of the automatic
focusing module 10; therefore, the second elastic element is also
referred to hereinafter as the upper spring plate 108.
[0031] The automatic focusing module 10 includes a voice coil motor
(VCM) provided in the base 101 of the automatic focusing module 10
and carrying the lens holder 102, which is located on the
image-capturing optical axis 7 (which is generally parallel to the
Z axis) and holds the lens 105. More specifically, the coil 103,
which is wound around the lens holder 102, and the plural magnets
104, which are provided on the inner periphery of the base 101 and
correspond to the coil 103, jointly form a VCM electromagnetic
driving module for driving the lens holder 102, and hence the lens
105 therein, linearly along the image-capturing optical axis 7. By
varying the current input into the coil 103, different magnetic
fields are generated between the coil 103 and the magnets 104 to
drive the lens holder 102 back and forth along the image-capturing
optical axis 7 so that zooming or focusing is carried out.
[0032] The lens holder 102 is provided in the base 101 and is
elastically clamped by the elastically movable inner rings of the
upper spring plate 108 (i.e., the second elastic element) and of
the lower spring plate 109. Both the upper spring plate 108 and the
lower spring plate 109 are elastic metal plates having thin
reticulated structures formed by stamping or etching. The upper
cover plate 106 covers the lens holder 102 and is connected to the
base 101 to limit the range in which the lens holder 102 can be
moved. The insulating plate 107 is located between the upper cover
plate 106 and the upper spring plate 108 and provides insulation.
The magnet fixing element 110 is provided at the bottom of the base
101 and corresponds to the compensation module 20. The two X-axis
magnets 111 are provided on the magnet fixing element 110 at
opposite positions. Likewise, the two Y-axis magnets 112 are
provided at opposite positions on the magnet fixing element 110.
The two Y-axis magnets 112 are located on the lateral sides of one
and the other of the two X-axis magnets 111.
[0033] The compensation module 20 is configured for moving the
automatic focusing module 10 horizontally, i.e., in a direction
perpendicular to the image-capturing optical axis 7 (or more
particularly, in the X-axis or Y-axis direction). The substrate 201
corresponds to the base 101 of the automatic focusing module 10.
The correction circuit board 202 is connected to the substrate 201
both physically and electrically. The two X-axis magnet driving
coils 203 are oppositely provided on the correction circuit board
202 and correspond to the two X-axis magnets 111. The two Y-axis
magnet driving coils 204 are oppositely provided on the correction
circuit board 202, are located on the lateral sides of one and the
other of the two X-axis magnet driving coils 203, and correspond to
the two Y-axis magnets 112. The X-axis displacement sensor 205 is
provided on the substrate 201 and is configured for detecting the
shift amounts of one of the two X-axis magnets 111. The Y-axis
displacement sensor 206 is also provided on the substrate 201 and
is configured for detecting the shift amounts of one of the two
Y-axis magnets 112. The X-axis displacement sensor 205 and the
Y-axis displacement sensor 206 can each be a displacement sensing
element composed of one of the following: a Hall sensor, a
magnetoresistance sensor (MR sensor), a fluxgate, an optical
position sensor, and an optical encoder. While the magnet driving
coils 203 and 204 in the embodiment shown in FIG. 2 are provided on
the correction circuit board 202, those magnet driving coils 203
and 204 may, in another embodiment (not shown), be directly
provided on the substrate 201 as well. In that case, the correction
circuit board 202 can be dispensed with.
[0034] The sensing module 30 is located below the compensation
module 20 and includes a circuit board 301 and an image sensing
element 302. The image sensing element 302 is provided on the
circuit board 301 and located on the same image-capturing optical
axis 7 as the automatic focusing module 10. The image sensing
element 302 of the sensing module 30 can capture light, or images,
from the outside through the automatic focusing module 10. The
suspension wires 5 are made of flexible wires. In addition, the
suspension wires 5, the upper spring plate 108, and the lower
spring plate 109 are all electrically conductive and serve as
conductive wires for delivering the driving current of the
automatic focusing module 10.
[0035] In the present embodiment, it is preferable that there are
four suspension wires 5 evenly distributed around the base 101,
with an equal spacing between each two adjacent suspension wires 5.
The connecting ends 51 of the suspension wires 5 are connected to,
and evenly distributed at the four corners of, the upper spring
plate 108 of the automatic focusing module 10. More particularly,
the connecting end 51 of each suspension wire 5 is connected to a
length-increased outer line element 1081 and at least one
additional auxiliary line element 1082 of the upper spring plate
108. Wherein, the additional auxiliary line element 1082 is spaced
from the outer line element 1081. Please refer to FIGS. 4 and 5
respectively for a schematic view and a partial enlarged view of a
spring plate in the optical image stabilizer according to the
present invention. The upper spring plate 108 has a thin
reticulated plate-like structure and includes: an outer frame 1085
connected to the base 101 of the movable portion 10, an inner frame
1086 connected to the lens 105-mounted lens holder 102, at least
one inner line element 1087 extending and connected between the
outer frame 1085 and the inner frame 1086, and a plurality of
coupling ends 1088 located on the outer frame 1085. The connecting
end 51 of each suspension wire 5 is connected to a corresponding
one of the coupling ends 1088. Each coupling end 1088 of the upper
spring plate 108 is connected to the outer frame 1085 by one outer
line element 1081 and at least one additional auxiliary line
element 1082. Each outer line element 1081 has one end connected to
the corresponding coupling end 1088 and the other end connected to
the outer frame 1085. Similarly, each additional auxiliary line
element 1082 has one end connected to the corresponding coupling
end 1088 and the other end connected to the outer frame 1085. In
this embodiment for example, the outer frame 1085 of the spring
plate 108 has a rectangular structure (which can be divided into
halves, i.e., two separate frame portions) and has four sides and
four corners. The coupling ends 1088 are located near the corners
of the rectangular outer frame 1085 respectively. The outer line
element 1081 and the at least one additional auxiliary line element
1082 that correspond to each coupling end 1088 are connected to two
adjacent sides of the outer frame 1085 respectively.
[0036] In other words, each of the four corners of the upper spring
plate 108 is provided with one coupling end 1088, which is
connected to the upper spring plate 108 by one length-increased
outer line element 1081 and at least one additional auxiliary line
element 1082. The coupling ends 1088 are provided for securing the
connecting ends 51 of the suspension wires 5 respectively. The
additional auxiliary line elements 1082 of the upper spring plate
108 are curvilinear and are respectively connected to the
corresponding coupling ends 1088 and hence the corresponding outer
line elements 1081 so as to reinforce the outer line elements 1081,
thereby preventing the maximum stress on the automatic focusing
module 10, when subjected to a drop test, from exceeding the
yielding stress of the outer line elements 1081. Should the former
stress exceed the latter, the automatic focusing module 10 could be
permanently (e.g., plastically) deformed. While only one additional
auxiliary line element 1082 is provided at each corner of the outer
frame 1085 in the present embodiment, it is feasible to provide two
or more additional auxiliary line elements 1082 at each corner of
the outer frame 1085 in other embodiments. Besides, while the upper
spring plate 108 (i.e., the second elastic element) and the plural
suspension wires 5 (i.e., the first elastic elements) in the
present embodiment are formed as independent and separate
components, the upper spring plate 108 (i.e., the second elastic
element) and the suspension wires 5 (i.e., the first elastic
elements) may be integrally formed as a single component in a
different embodiment (not shown). For example, but without
limitation, the suspension wires 5 are integrally formed with the
upper spring plate 108 by a stamping or etching process such that
the suspension wires 5 extend respectively and horizontally from
the coupling ends 1088. Afterward, the suspension wires 5 are bent
downward by 90 degrees, thus making the suspension wires 5 extend
in a direction perpendicular to the horizontal surfaces of the
upper spring plate 108.
[0037] The fixed end 52 of each suspension wire 5 is generally
perpendicular to the Z axis and is fixed to the compensation module
20. In consequence, the automatic focusing module 10 is supported
and secured above the compensation module 20 with a predetermined
spacing therebetween. The material properties of the suspension
wires 5 allow the automatic focusing module 10 to move
perpendicular to the image-capturing optical axis 7, i.e., along
the X-axis and Y-axis directions. The length of each suspension
wire 5 preferably ranges from 2 mm to 3 mm and more preferably is
2.7 mm. The diameter of each suspension wire 5 preferably ranges
from 0.04 mm to 0.05 mm and more preferably is 0.045 mm. In this
embodiment, the suspension wires 5 are made of a material whose
Young's modulus is 120000 MPa.
[0038] Differently put, the four suspension wires 5 support the
automatic focusing module 10 (i.e., the movable portion) in such a
way that the automatic focusing module 10 is securely located a
predetermined distance above the compensation module 20 and is on
the same image-capturing optical axis 7 as the sensing module 30,
which is below and corresponds to the compensation module 20. The
suspension wires 5 not only provide support against gravity but
also, due to the flexibility of the suspension wires 5, enable
displacement correction of the automatic focusing module 10 along
the X axis and the Y axis. The X-axis displacement sensor 205 and
the Y-axis displacement sensor 206 can sense the horizontal shift
amounts of the automatic focusing module 10 in relation to the
sensing module 30 while the optical image stabilizer 1 is shaken.
Based on the sensing results, the two X-axis magnet driving coils
203 and the two Y-axis magnet driving coils 204 on the correction
circuit board 202 respectively drive the two X-axis magnets 111 and
the two Y-axis magnets 112 fixed on the magnet fixing element 110
below the automatic focusing module 10, thereby correcting the
lateral shift amounts of the automatic focusing module 10, i.e.,
the amounts by which the automatic focusing module 10 has been
shifted perpendicular to the image-capturing optical axis 7 (i.e.,
along the X axis and the Y axis). Consequently, the desired
anti-shake function is achieved, allowing the images thus captured
to have better image quality.
[0039] Reference is now made to FIGS. 4 through 6, wherein FIG. 6
schematically shows a spring plate in a conventional optical image
stabilizer. In the present invention, the outer line elements 1081
of the upper spring plate 108 are increased in length to prevent
permanent deformation (e.g., plastic deformation) which may
otherwise occur if the maximum stress generated in a drop test
exceeds the yielding stress of the outer line elements 1081.
Furthermore, the outer line elements 1081 are reinforced by the
additional auxiliary line elements 1082. With the length L2 of each
additional auxiliary line element 1082 being greater than the
length L1 of the corresponding outer line element 1081 (i.e.,
L2>L1), and the width of each additional auxiliary line element
1082 being less than that of the corresponding outer line element
1081, the automatic focusing module 10 is kept from excessive
gravity-induced downward (Z-axis) displacement while at rest.
According to applicable standards in the industry, the
gravity-induced downward (Z-axis) displacement of the automatic
focusing module 10 (i.e., the movable portion) in a rest state
should be less than 0.005 mm.
[0040] Please refer to Table 1 for the stresses (MPa) experienced
by the spring plate and the suspension wires of the conventional
optical image stabilizer depicted in FIG. 6 in a simulated drop
test in which the X-, Y-, and Z-axis displacement parameters (mm)
of the movable portion (i.e., the automatic focusing module) are
separately set.
TABLE-US-00001 TABLE 1 Simulated displacements of Conventional
spring plate (stress) the movable portion along Suspension Spring
the X, Y, and Z axes (mm) wires (MPa) plate (MPa) X = 0.15 Y = 0.15
Z = 0.1 1945 1694
[0041] As shown in FIG. 6, the conventional spring plate 4 is
connected to each suspension wire 5 by a single and relatively
short outer line element 41. Besides, the yielding stress of the
suspension wires 5 ranges generally from 930 to 1180 MPa, and the
yielding stress of the conventional spring plate 4 is generally
1080 MPa. In the drop test, the simulated X-, Y-, and Z-axis
displacement parameters of the movable portion are respectively set
at 0.15 mm, 0.15 mm, and 0.1 mm according to the greatest possible
displacements of the movable portion if the movable portion is
actually dropped. When the movable portion equipped with the
conventional spring plate 4 is subjected to the drop impact, the
suspension wires 5 experience a stress of 1945 MPa, which is far
greater than the yielding stress of the suspension wires 5 (i.e.,
930 to 1180 MPa). At the same time, the spring plate 4 subjected to
the drop impact is under a stress of 1694 MPa, which is far greater
than the yielding stress of the conventional spring plate 4 (i.e.,
1080 MPa). It can be known from the drop test data that both the
conventional spring plate 4 and the suspension wires 5 will be
permanently (e.g., plastically) deformed by the drop impact in
practice.
[0042] As stated above, the stresses to which the spring plate 4
and the suspension wires 5 of the conventional optical image
stabilizer are subjected to during the simulated drop test are
greater than their respective yielding stresses (MPa). In light of
this, the spring plates of the optical image stabilizer according
to the present invention as shown in FIGS. 4 and 5--particularly
the upper spring plate 108 fixed in the automatic focusing module
10--are so designed that each of the four corners of the upper
spring plate 108 is provided with the length-increased outer line
element 1081 and the additional auxiliary line element 1082 for
firmly connecting with the connecting end 51 of the corresponding
suspension wire 5. In addition, the fixed ends 52 of the suspension
wires 5 are fixed to the compensation module 20 such that the
automatic focusing module 10 is supported a predetermined distance
above the compensation module 20. The foregoing design not only
allows the automatic focusing module 10 to have a gravity-induced
downward displacement less than 0.005 mm in a rest state, but also
allows the stresses generated in the upper spring plate 108 and in
the suspension wires 5 when subjected to a drop impact to be less
than their respective yielding stresses (i.e., 930 to 1180 MPa and
1080 MPa, respectively). Therefore, when not subjected to any drop
impact, the upper spring plate 108 can bear the stress of
supporting the automatic focusing module 10, and when the automatic
focusing module 10 is moved and deforms the upper spring plate 108,
the resultant stress will not exceed the yielding stress of the
upper spring plate 108, thus allowing the upper spring plate 108 to
bring the automatic focusing module 10 back to its original
position resiliently.
[0043] Table 2 shows the stresses (MPa) of a spring plate and the
suspension wires of the optical image stabilizer according to the
present invention in a simulated drop test in which the X-, Y-, and
Z-axis displacement parameters (mm) of the movable portion (i.e.,
the automatic focusing module) are separately preset.
TABLE-US-00002 TABLE 2 After the outer line elements of the upper
When the additional auxiliary line spring plate are increased in
length elements are provided Gravity-induced Gravity-induced
downward downward Upper displacement of Upper displacement of
Simulated displacements of spring the movable spring the movable
the movable portion along Suspension plate portion at rest
Suspension plate portion at rest the X, Y, and Z axes (mm) wires
(MPa) (MPa) (mm) wires (MPa) (MPa) (mm) X = 0.15 Y = 0.15 Z = 0.1
871 734 0.0152 929.5 880.9 0.00386 X = 0.15 Y = 0.15 Z = -0.1 912.2
934.5
[0044] According to Table 2, after the length of each outer line
element 1081 of the upper spring plate 108 of the disclosed optical
image stabilizer is increased, the outer line elements 1081 are
allowed sufficient deformation to suppress deformation of the
suspension wires 5 under a drop impact; consequently, the maximum
stress of the suspension wires 5 is reduced. However, simply
increasing the lengths of the outer line elements 1081, to which
the suspension wires 5 are respectively connected, is not enough,
for in the absence of the additional auxiliary line elements, and
under the drop impact set by the X-, Y-, and Z-axis displacement
parameters (0.15 mm, 0.15 mm, and 0.1 mm, respectively) of the
automatic focusing module 10 (i.e., the movable portion) in the
drop test, the gravity-induced downward displacement of the
automatic focusing module 10 (i.e., the movable portion) at rest is
as great as 0.0152 mm, which does not meet the requirement of being
less than 0.005 mm. In other words, if permanent deformation is to
be prevented in the drop test only by increasing the lengths of the
outer line elements 1081, the outer line elements 1081 will be so
pliable that the movable portion undergoes excessive Z-axis
displacement at rest. Therefore, in addition to increasing the
lengths of the outer line elements 1081, the additional auxiliary
line elements 1082 are required for assisting the outer line
elements 1081 in supporting the weight of the automatic focusing
module 10 and the impact of the drop test. In order not to
compromise deformation of the outer line elements 1081, the length
L1 of each additional auxiliary line element 1082 must be greater
than the length L2 of the corresponding outer line element 1081.
Furthermore, the thickness of the upper spring plate 108 preferably
ranges from 0.3 mm to 0.5 mm and more preferably is 0.4 mm, and the
Young's modulus of the upper spring plate 108 is 127000 MPa.
[0045] Referring again to Table 2, when the lengths of the outer
line elements 1081 are increased, and the additional auxiliary line
elements 1082 are provided, with lengths greater than those of the
corresponding outer line elements 1081 (i.e., L2>L1), the
suspension wires 5 are subjected to a stress of 929.5 MPa, and the
upper spring plate 108 to a stress of 880.9 MPa, under the drop
impact set by the X-, Y-, and Z-axis displacement parameters (0.15
mm, 0.15 mm, and 0.1 mm, respectively) in the drop test. When the
X-, Y-, and Z-axis displacement parameters are set at 0.15 mm, 0.15
mm, and -0.1 mm, respectively, the resultant drop impact causes a
stress of 912.2 MPa on the suspension wires 5, and a stress of
934.5 MPa on the upper spring plate 108. All the stresses stated
above conform to the requirement that the stress of the suspension
wires 5 be lower than the range from 930 to 1180 MPa and that the
stress of the upper spring plate 108 be lower than 1080 MPa. The
gravity-induced Z-axis displacement (0.00386 mm) of the movable
portion 10 at rest also meets the requirement that the Z-axis
displacement be less than 0.005 mm. Thus, the afore-mentioned
drawbacks of the prior art are overcome.
[0046] Please refer to FIGS. 7A and 7B for the second and the third
embodiments of the suspension wires of the optical image stabilizer
according to the present invention. Aside from the structure
depicted in FIGS. 2 and 3 which is a single-line structure
extending in the Z-axis direction, each suspension wire of the
disclosed optical image stabilizer may have a suspension wire 5a
structure formed with a continuous S-shaped flexible portion (i.e.,
the second embodiment shown in FIG. 7A) or a suspension wire 5b
structure formed with a spiral spring-shaped flexible portion
(i.e., the third embodiment shown in FIG. 7B). The upper ends
(i.e., the connecting ends 51a, 51b) and the lower ends (i.e., the
fixed ends 52a, 52b) of the suspension wires 5a, 5b are connected
to the coupling ends 1088 of the upper spring plate 108 and the
substrate 201 of the compensation module 20 respectively, as in the
previous embodiment. The continuous S-shaped or spiral
spring-shaped flexible portion not only provides the suspension
wires 5a, 5b with relatively great horizontal flexibility (i.e., in
the X- and Y-axis directions), but also allows the suspension wires
5a, 5b to extend slightly in the Z-axis direction.
[0047] While the present invention has been particularly shown and
described with reference to a preferred embodiment, it will be
understood by those skilled in the art that various changes in form
and detail may be without departing from the spirit and scope of
the present invention.
* * * * *